Circuit with an opto-electronic display unit

ABSTRACT

A circuit provided with an optoelectronic display unit. For discrete display of the settings of a regulating/control unit, said circuit comprises at least one detection element for detecting the actuation of an object in order to modify the settings of the regulating/control unit, whereby the detection element delivers an output signal corresponding to the desired modification. Several luminous diodes ( 1   a   , . . . , 1   n ), which are essentially arranged next to each other in a row and which emit luminous radiation, are used as display elements. A control device controls at least one of the luminous diodes ( 1   a   , . . . , 1   n ) according to the output signal in order to display the respective setting, in addition to the regulating/control unit for modification of the setting. In order to produce a quality display and operator unit, at least two receiver elements which are sensitive with respective to the luminous radiation of the luminous diodes ( 1   a   , . . . , 1   n ) are provided, acting as detection elements in order to detect the luminous radiation reflected by at least one luminous diode ( 1   c ) and by an object ( 2 ), and the control device controls at least one of the luminous diodes in addition to the regulating/control unit as a result of the output signal, which is formed according to the movement of the object relative to the luminous diode ( 1   c ) emitting luminous radiation, according to the movement of said object.

REFERENCE TO RELATED APPLICATIONS

The present application claims the priority of the German patentapplication 101 46 996.9, filed on Sep. 25, 2001, the disclosure contentof which is hereby expressly also made the subject matter of the presentapplication.

FIELD OF THE INVENTION

The invention relates to a circuit comprising an optoelectronic displayunit.

BACKGROUND OF THE INVENTION

In the field of operator control elements, displays formed e.g. by aseries of LEDs are known, which indicate a set value. This may be a rowof LEDs, i.e. light-emitting diodes, which are arranged side by side andof which one element emits light and indicates an actual value. As arule, the luminescent elements arranged in a row are suitably labelledto enable an association with a quantity such as e.g. a display in “dB”for volume control. Changeover to another value is effected mechanicallye.g. by means of momentary-contact switches. Generally, to increase andreduce the value one mechanical momentary-contact switch is used in eachcase. A change of value effected by pressing the appropriatemomentary-contact switch is indicated by the appropriate LED in the rowby virtue of a positional variation in the display.

FIG. 1 shows such an LED display known from the prior art, wherein theposition of the LED and hence also e.g. the “volume level” may beadjusted by means of the plus and minus keys. The advantage of such anarrangement lies in the clear overview of the set position and in thespontaneous operator controllability. The drawback is, however, the needfor mechanical cutouts in the operator control panel and the provisionof appropriate keys.

From DE 43 36 669 C1 a touch panel is known, comprising optical sensors,which are associated with different actuating surfaces and react to theshading of a sensor surface corresponding to the size of a finger. Theacquisition of the ambient light is therefore the information to beprocessed. Usually, for this purpose, a means other than the means usedto generate a light signal is used. For indicating a value that is to bedisplayed an additional lighting display unit is required. Theopto-receivers and opto-transmitters may be operated exclusively in apulsed manner, which is disadvantageous for the discrete alteration of avalue that is to be set (cf. also DE 40 07 971 A1 in the infraredrange).

The acquisition of information, which is needed to vary a value to beset at an operator panel, may also be effected by means oftouch-sensitive switching devices according to DE 694 19 735 T2 or DE 3685 749 T2, which through the acquisition of a capacitance correspondwith the optical display unit to be operated; because of its sensitivityto moisture, however, this use is restricted to specific areas.

DE 39 32 508 A1 shows a conventional reflection light barrier without adiscrete control facility. Transmitters and receiving elements alwayshave to be provided separately. DE 28 24 399 A1 discloses an opticalswitch with separate transmitters and receivers. In both cases, thelight barriers formed thereby are only the means of setting the displayand not the display means itself.

From U.S. Pat. No. 5,327,160 a touch fader as a remote control is known,which may be operated only in the switching mode.

Arrangements of light-emitting diodes, which may be used in turn both asa light-emitting and as a light-receiving element and the optical signalof which directly reproduces the value to be displayed, which maymoreover be controlled so as to follow the movement of a finger or of acomparable body in order thereby to reach the value to be set, but whichmay also be operated in clocked manner and thus spontaneously, are notknown from the prior art.

SUMMARY OF THE INVENTION

Proceeding from this background art, an advantage of one or more ofvarious embodiments of the invention is to provide an advantageousdisplay- and operator control unit and, for operator control of such aregulating/adjusting unit, to utilize the display itself as an operatorcontrol element, wherein both discrete regulation of values to be setand clocked handling is possible.

In an exemplary embodiment, a circuit with an optoelectronic displayunit for the discrete display of the setting of a regulating/adjustingunit includes: at least one detection element for detecting theactuation of the regulating/adjusting unit by means of a body forchanging the setting of the regulating/adjusting unit, wherein thedetection element upon actuation supplies an output signal correspondingto the desired change; a plurality of light-emitting diodes disposedsubstantially side by side in a row and emitting optical radiation, thelight-emitting diodes being formed as display elements of the displayunit; a control device, which in dependence upon the output signalproduced by the detection element controls at least one of thelight-emitting diodes to display the respective setting as well as theregulating/adjusting unit to change the setting; wherein the controldevice controls at least one of the light-emitting diodes, the detectionelements as well as the regulating/adjusting unit to follow the movementof the body on the basis of the output signal, which is formed independence upon the movement of the body relative to the light-emittingdiode that is emitting optical radiation, and that either at least tworeceiving elements are provided, which are sensitive to the opticalradiation of the light-emitting diodes and which as the detectionelements detect the optical radiation emitted by at least onelight-emitting diode and reflected by the body, or that at least onereceiving element is provided, which is sensitive to the opticalradiation of the light-emitting diodes and which as the detectionelement detects the optical radiation emitted by at least twolight-emitting diodes and reflected by the body, wherein in both casesthe control device, as soon as the control device because of the outputsignal advances the display unit in one direction to one of the nextlight-emitting diodes, also advances in the same direction the receivingelement(s) being adjacent to the light-emitting diode emitting theoptical radiation.

With the display unit formed by the light-emitting diodes receivingelements are associated in such a way that no separate mechanical keysare necessary. For operator control of such a regulating/adjusting unit,therefore, the display itself becomes the operator control element.There is therefore no need for either keys or cutouts for such keys.This, on the one hand, reduces the cost of manufacturing such anoperator control unit and, on the other hand, enables theregulating/adjusting unit to be disposed under a closed, protectivesurface so that it—easy to clean and insensitive to dirt—has a longuseful life and may be used for many applications.

In another exemplary embodiment, the light-emitting diodes are not onlya display element but temporarily in turn a transmitting and receivingelement, thereby making it possible further to reduce the circuitengineering outlay.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in detail below with reference to theaccompanying drawings. The drawings show:

FIG. 1 a regulating/adjusting unit according to prior art,

FIG. 2 a block diagram of a regulating/adjusting unit according to priorart,

FIG. 3 a diagram for selection of an LED as a display- and operatorcontrol element,

FIG. 4 a reflecting element usable for operator control above an LEDrow,

FIG. 5 an arrangement for realizing a sensitive LED row,

FIGS. 6, 7 the circuit according to the invention,

FIGS. 8 a-8 e signal characteristics during momentary contact with anLED,

FIG. 9 a circuit for selection of an outer-lying LED,

FIG. 10 phases and amplitude relationship of the analogue output signalS17 of the comparator 16,

FIG. 11 the analogue output signal S17 over time during changeover,

FIG. 12 a circuit for increasing the changeover reliability,

FIGS. 13, 14 the analogue output signal S17 over time across the outputof the buffer B with and without zero referencing,

FIG. 15 the signal V1, derived from the analogue output signal S17, overtime at the window comparator according to FIG. 14 with associated LEDselection,

FIG. 16 a circuit according to FIG. 12 with a hysteresis detector,

FIG. 17 a signal characteristic of the output signal S17 withsimultaneous use of the hysteresis detector,

FIGS. 18 a-18 c arrangements for use as a volume control, for processinga data stream or as a position display,

FIG. 19 a mechanical sliding control according to prior art,

FIGS. 20, 21 arc-shaped and circular regulating/adjusting unitsaccording to the invention,

FIG. 22 a regulating/adjusting unit in the form of a virtual turningknob,

FIG. 23 a regulating/adjusting unit with two transmitting elements,

FIG. 24 a complete block diagram.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The invention is described in detail below with reference to theaccompanying drawings. However, the embodiments are merely examples,which do not restrict the inventive concept to a specific arrangement.

In the prior art, the switching assignment for an adjusting unitaccording to FIG. 1 comprises according to FIG. 2 a counting device 91,the instantaneous state of which is determined by the key functions T1(e.g. +key) and T2 (e.g. −key). Each time the keys T1 and T2 areactuated, the counting device 91 counts one value increment upwardsand/or downwards and passes this information on to the display driver92, which allows the LED corresponding to the set value to emit light.Parallel thereto, the set value is passed on to the control apparatusand/or the value regulator 93. This value regulator 93 regulates e.g.the amplitude of an analogue audio signal 94/95 in accordance with theset value 96. Thus, always at least one external control signal T1 or T2is required for setting the value. The LEDs 1 a . . . n merely displaythe set value and have no other function.

The invention described below dispenses with indirect informationtransfer with the aid of the keys T1 and T2, with the result that theinformation is received up and converted directly by the LED display.

To achieve this, the bifunctionality of the light-emitting diodes isused: these may emit light, when they are correspondingly driven by acurrent, or produce power and/or current, when they are correspondinglyilluminated. If then, for example, low-crosstalk wiring is selected, alight-emitting diode may be operated sequentially as a transmitter andas a receiver. In principle, the same function is however realizablealso by using alternative receiving elements such as e.g. photodiodesparallel to the light-emitting LEDs. In this case too, because of theoverall size the display is still simultaneously the operator controlelement, even when the light-emitting diodes do not have the abovedouble function.

FIG. 3 shows such wiring, where the light-emitting diodes (LEDs) operatesequentially in respect of time as transmitters and receivers. In thephase t_(x) the switch Sa, for example, is closed and connects theoutput of the clock generator 100 to the LED via the series resistorR₁₀. The clock generator is operated e.g. at a frequency of 10 kHz. Inthis phase the switch Sb is open and disconnects the LED from theamplifier 300. The inverter 200 is used only to invert the controlsignal Sts. In phase t_(y) the switch relationship is reversed and theswitch Sa disconnects the LED from the clock generator 100, while switchSb connects the LED to the amplifier 300.

To present a display, generally at least one element of an LED row willemit light, while all of the others are switched off. Naturally, thereare however also constructions where all of the display elements up tothe set value are switched on, i.e. form a light strip. If thelight-emitting element of the LED row emits its light, not as constantlight by virtue of continuous selection, but in a pulsed manner e.g. bymeans of a 10 kHz rectangular-pulse signal, it nevertheless appears tothe naked eye as a continuously light-emitting element. At the sametime, it may however be used as a transmitting element of a sensorapparatus. Adjacent LEDs, which are correspondingly connected asreceivers, may namely receive the signal of the pulse-controlled LEDwhen a reflecting element, e.g. a finger 2, is situated above the LEDthat is emitting the pulsed light.

Given a positioning of the reflecting element centrally above thetransmitting LED 1 c according to FIG. 4, the emitted light is reflecteduniformly onto the adjacent LEDs 1 b and 1 d. In said case, a pane 37,which is translucent with regard to the respective radiation emitted bythe LED may also be situated between the LEDs and the reflectingelement, e.g. a finger 2. As radiation, in particular, all opticalradiation in the visible range but also in the range invisible to thehuman eye is suitable. Given symmetrical reflection, there is alsoacross the outputs of the amplifiers 5 and 6 an amplitude of equal sizein the output signals 7, 8.

FIG. 5 shows an arrangement for realizing the sensitive LED row. Thelight-emitting diodes 1 a . . . 1 n may be utilized both in thetransmitting and in the receiving range. For the transmitting mode ofthe light-emitting diodes 1 a . . . 1 n, connectable driver stages 3 a .. . 3 n are provided and, for the receiving range, connectableamplifiers 2 a . . . 2 n are provided. The signal distribution stages 44and 45 are suitably positioned by the setting of the position counter23. The direction decision unit 47 detects the direction of motion ofthe reflecting element and decides when a specific value of the positiondeviation has occurred. If this was the case, position counter 23 iscorrespondingly activated and counts one position value upwards ordownwards. At the same time, the direction decision unit 47 may first ofall establish whether there was “momentary contact” of thelight-emitting element before reacting to movement e.g. of the finger 2,or whether it was a case of inadvertent touching of the sensor-activesurface and hence no reaction of the LED display is to occur.

The position counter 23 via a control unit 24 (FIG. 7) controls both theselection of the transmitter elements and the receiving mode. In eachcase, therefore, a single LED is selected as a transmitter, while atleast the LEDs adjacent to it—e.g. the next or next but one LED—areconnected as receivers. However, it is of course also possible for twoLEDs to transmit simultaneously and for the LED disposed between the twolight-emitting LEDs to be connected as a receiver. In principle, it isalso possible for separate receiving elements to be arranged staggeredor offset relative to the LEDs, e.g. in a row parallel to the LEDs. Atthe position counter 23, moreover, the control signal Sts forinfluencing any desired regulating/adjusting unit 30 is tapped.

FIG. 6 shows a circuit for direction detection, momentary contactrecognition and detection of the horizontal movement of the reflectingelement in relation to the light-emitting LED, here LED 1 c. Here, LED 1c is selected by the clock generator 100 and is emitting light, which isreflected by the finger 2. The adjacent LEDs 1 b, 1 d receive areflection component caused by the finger 2. DCCs 3, 4 form an operatingpoint adjustment for the LEDs as receivers. With the aid of these DCCs(DC compensation), even in the event of intense extraneous light theLEDs are prevented from becoming saturated. The construction of such anoperating point adjustment is known e.g. from DE-PS 44 31117.

For the sake of simplicity the changeover switches of the LED selectionare not shown in the drawing. Two amplifiers 5 and 6 of an identicaltype amplify the low output signals of the LEDs 1 b and 1 d adjacent tothe transmitter to a value that is easy to process further. Before bothoutput signals 7 and 8 are combined in the summing stage 10, theinverting circuit 9 inverts one of the two signals.

Given the absence of a reflecting element, such as a finger 2, or giventhe presence of one but with symmetrical reflection of the transmittedsignal back into LEDs 1 b, 1 d, no signal occurs across the output ofthe summing stage or because of the inverting circuit 9 two signalcomponents, which for instance arise but are of equal magnitude, canceleach other out so that there is likewise no signal across the output ofthe summing stage 10. Given the presence of a reflecting element andsimultaneous asymmetry relative to the transmitting LED 1 c, e.g. if thefinger 2 has shifted slightly to the right, at the LED 1 d owing tointensified reflection a greater signal develops than at the LED 1 b.This leads, across the output of the summing stage 10, to a signal witha clocked modulation with corresponding sign of the phase in relation tothe signal of the clock generator 100. The magnitude of the signal isdetermined by the horizontal position of the finger 2 in relation to thetransmitting LED 1 c.

The output signal of the summing stage 10 is supplied for furtherevaluation to a synchronous demodulator 11. The control signal for thesynchronous demodulator is tapped from the clock generator 100. Itcorresponds substantially to the transmitted signal but takes intoaccount the phase displacements arising in the amplifiers 5 and 6. Thesynchronous demodulator 11 splits the output signal of the summing stage10 once more into two individual signals 12, 13 associated with the LED1 b and 1 d respectively. For a clear decision about the direction ofmotion and/or position of the finger 2 relative to the transmittingelement 1 c, the two individual signals 12 and 13 are compared with oneanother in the comparator 14. The digital output signal S15 of thecomparator 14 provides clear information about the position of thereflecting element, in relation to the transmitting element 1 c, i.e.about whether the finger 2 is situated to the right or left of thecentre of the LED 1 c.

In order to decide, from which position variation an advancing of thelight-emitting LED analogous to the movement of the finger 2 is tooccur, the output signals 12 and 13 of the synchronous demodulator 11are compared in a suitably analogue-operating comparator 16, e.g. withan operational amplifier. The analogue output signal S17 corresponds tothe horizontal deviation of the finger from the centre of thetransmitting LED 1 c. From this output signal during further signalprocessing the switching signal for the position counter 23 (FIG. 7) isobtained. The digital output signal S15 is used to define theappropriate counting direction for the position counter 23. In theembodiment, a counting direction towards higher values may advance thetransmission driver from the LED 1 c to the LED 1 d, with a simultaneouschangeover of the amplifiers 5 and 6 from LED 1 b and 1 d to 1 c and 1e.

To prevent unintended adjustment owing to inadvertent contact, prior“momentary contact” of the light-emitting element for further activationof the adjustment facility may be provided. For this purpose,information has to be obtained from the vertical movement of the finger2 towards or away, respectively, from the light-emitting element. Thisinformation may be gathered from the summing stage 18, in which bothsignals of the receiving LEDs are summed. A synchronous demodulator 19correspondingly evaluates the summed signal and said signal is availablevia the buffer stages 20 as an analogue distance signal S21.

FIG. 7 shows the evaluation of the signals S21, S15 and S17. A windowcomparator 22 supplies an output signal S22 when the output signal S17,which is in fact an analogue value of the horizontal position of thefinger in relation to the transmitting LED, exceeds or falls below avalue preselected in the window comparator 22. This value is reachedwhen the reflective element, i.e. the finger 2, is moved some distancelaterally of the centre of the transmitting element (LED 1 c) towardsthe adjacent receiving element (LED 1 b or 1 d), even if the distance isless than half the distance between two adjacent elements. The outputsignal S22 of the window comparator 22 is supplied as a clock signal tothe position counter 23.

The decision, whether the position counter 23 is to count upwards ordownwards, which corresponds to a “shift” of the light-emitting LED tothe left or to the right, is taken from the output signal S15 of thecomparator 14. The output signal S23 of the position counter 23 issupplied to the control unit 24. The control unit 24 determines theposition—corresponding to the numerical value of the output signalS23—of the transmitting LED and its at least two indirectly or directlyadjacent receiving LEDs or receiving elements.

In principle, the light-emitting LED is not to change position simply asa result of a hand being inadvertently wiped over the LED. Rather, firstthe position sensitivity is to be activated manually before thelight-emitting LED “travels along” with the moving finger. For thispurpose, the output signals 7, 8 are combined in the summing stage 18and synchronously demodulated and the distance signal S21 thus obtainedis conditioned in a suitable evaluation circuit 25 in such a way thate.g. a shift of position is enabled only after “momentary contact” withthe light-emitting LED has been effected once or twice.

The momentary-contact recognition apparatus preferably recognizes asmomentary contact a pattern of motion, which comprises the approach of abody, the sudden braking of the body against a touched surface and adwelling on the surface for a preselected time t28.

To this end, in the embodiment the distance signal S21 is passed throughthe high-pass filter 26, which allows through only the higher-frequencyspectral components of the distance signal S21. These signal componentsoccur only in the event of a rapid variation in the distance signal S21according to FIG. 8 a. The sudden braking of the finger on a translucentsurface above the LED row may therefore lead to an output signal S26, asignal differentiated from the distance signal S21. If this outputsignal S26 according to FIG. 8 b exceeds a predetermined value Ref, thecomparator 27 supplies a digital output signal S27 (FIG. 8 c) to a firsttimer 28 with a timer time t28 of several hundred milliseconds toseconds (FIG. 8 d). At the end of this short time, timer 29 according toFIG. 8 e is started. Its running time is several seconds. The outputsignal S29 enables the position counter 23. A variation of the countercontent then retriggers (rt) the timer 29. If the position of thelight-emitting LED is not varied within the running time t29 of thetimer 29, the time t29 elapses and the position counter 23 is disabledagain. This circuit arrangement prevents the position of thelight-emitting LED in the LED row from being varied by an unintentionalmovement. It is only after “momentary contact” that the position of thelight-emitting LED may be shifted by renewed contact with thelight-emitting LED and displacement of the finger.

At this point any conceivable circuit arrangement may be inserted, i.e.including counter arrangements, which also enable the position counter23 only after repeated momentary contact with the light-emitting LED.From WO 01/54277 A1 an arrangement—which is e.g. preferentially usablehere—is known, in which a function is switched only if a finger quicklytouches (has momentary contact with) the translucent surface above anLED and remains relatively still there for at least a specific time,e.g. 200 ms.

The digital output signal S23 of the position counter 23 moreovercontrols the control unit 24. In the control unit 24, the transmitteddrive signal is suitably distributed to the LEDs and the two amplifierinputs of the amplifiers 5, 6 (FIG. 6) are distributed to the LEDsadjacent to the transmitting diodes. The output signal S23 of theposition counter 23 (FIG. 7) may further be used to control any desiredvalue controller of a regulating/adjusting unit 30, e.g. for volumecontrol.

If the light-emitting LED is “shifted” into one of the two endpositions, it is however no longer possible for the at least twoadjacent LEDs to serve as receivers, but only one. In said case, in theevent of parasitic reflections e.g. at the translucent surface, thesingle receiving LED, e.g. LED 1 a, receives a signal similar to that ofa “shifted” finger. In extreme cases, this unwanted signal would lead tothe selection repeatedly skipping back from LED 1 a to LED 1 b.

To prevent this, upon selection of LED 1 a a simulated “light signal” ispresented to the amplifier 6 (FIG. 6). FIG. 9 shows the correspondingchangeover in said respect. Switches S1, S2 and S3 are activated via thecontrol unit 24 by the control signal S23 of the position counter 23(FIG. 7). Switch S1 connects the output of the clock generator 100 tothe appropriate LED. In the embodiment, in FIG. 9 to the LED 1 a, i.e.out on the far left. Switch S3 connects the amplifier input of theamplifier 5 to the LED 1 b lying adjacent on the right. Switch S2connects the amplifier input of the amplifier 6 to a voltage dividerR₁/R₂, which is connected to the output of the clock generator 100. Thedivider ratio of the voltage divider R₁/R₂ is so dimensioned that themagnitude of the divided-down transmitted clock signal is slightlygreater than the received signal of LED 1 b produced by parasiticreflection at the translucent surface.

It is thereby guaranteed that, when the finger is moved over the LEDrow, e.g. from the middle to the left over LED 1 a, the latter as thelast LED in the row emits light. If, on the other hand, the finger ismoved from the side across the light-emitting LED 1 a towards the middleof the LED row, then in the position of the finger 2 between LED 1 a and1 b the reflection of the transmitting LED 1 a at the finger willproduce a greater signal than was supplied by the voltage divider R₁/R₂.The phase angle of the signal S10 (FIG. 6) is therefore reversed and theselection of LED 1 a switches over to LED 1 b, and/or follows the finger2.

With the previously described arrangement for controlling the LED rowthe light may of course be shifted by the finger only in one directionin each case. The reason for this is that, from a specificdistance—determined by the threshold values defined in the windowcomparator 22 (FIG. 7)—of the finger from the centre of the actuallylight-emitting LED, the light shifts in front of the moving finger 2. Ifby virtue of continuous finger movement the actually light-emitting LEDis passed over again, the light switches in front of the finger to thenext LED and so on. If, however, after a shift the finger 2 stops and ismoved back, the last light-emitting LED remains in its last position. Toreverse the direction of motion, the finger then has to be placed—viewedin the direction of motion—in front of the light-emitting LED. It has tobe passed over in the, then, reverse direction of motion. The displaythen follows the finger position once more.

However, as this is impractical in general use, between the comparator16 (FIG. 6) and the window comparator 22 (FIG. 7) a circuit is inserted,which ensures that the light spot always directly follows the fingermovement. This circuit arrangement utilizes the effect whereby duringthe changeover from one LED to the next LED the polarity of the countercontrol signal (output signal S15) and of the analogue output voltage ofthe comparator 16 (output signal S17) is reversed. This is easy toexplain if one considers that the changeover occurs when the fingermoves e.g. to the right away from the light-emitting LED and the LEDsituated on the right of this LED detects an increased reflection. Ifthis value exceeds a predetermined quantity, then the window comparator22 supplies a corresponding signal and the position counter 23 (FIG. 7)counts one value “upwards”, in this case therefore to the “right”. Theoriginally light-emitting LED “shifts” from the, relative to the finger2, left position to the position on the right of the finger. The LEDoriginally connected as a light-emitting element changes its functionand becomes the opto-receiver, which is however now situated on the leftof the transmitting element. However, as the finger 2 is still situatedin an approximately identical position, the LED situated on the left ofthe transmitting element then receives more reflection than the LEDsituated on the right of the transmitting element. This however means,across the output of the summing stage 10 (FIG. 6), a reversal of thephase and hence also a reversal of the polarity of the digital outputsignal S15 and also of the analogue output signal S17.

FIG. 10 describes the phases and amplitude relationship of the analogueoutput signal S17 (FIG. 6) of the comparator 16 in such a case. Position51 or LED 1 a . . . 1 n, respectively, show the mechanical arrangementof the LEDs, 52 the associated signal values of the analogue outputsignal S17 of the comparator 16. 53 corresponds in the illustrated caseto a signal, when LED 1 c is emitting light. If during a finger movementto the right the output signal S17 of the comparator 16 falls below thepreselected lower threshold value US, the position counter 23 counts onecounter upwards (54 in FIG. 10). The counter setting determines whichLED is selected in switching mode (55 FIG. 10). The solid bold line 56shows the characteristic of the output signal S17 of the comparator 16when a finger 2 is moved from left to right over the LED row.

In the changeover situation, the threshold value OS of the windowcomparator 22 is again—in a different polarity—exceeded and so theposition counter 23 will count back again. A continuous changeover ofthe LED positions symmetrically relative to the finger 2 would be theresult. The light-emitting LEDs follow the finger 2 in that, when thefinger is positioned centrally on an LED, only this LED emits light,whereas, when the finger is positioned between two LEDs, both emit lightin rapid alternation.

For tolerances reasons, however, after a first overshooting of thethreshold value US a changeover may be effected, after which thethreshold value OS is in turn overshot and a second changeover iseffected back to the original position, only this time the thresholdvalue US is not undershot so that a further changeover is not absolutelyguaranteed. Upon movement of the finger over the LED row the display mayconsequently “become stuck”.

FIG. 11 shows the analogue output signal S17 (FIG. 6) of the positionrecognition comparator 16. In section 61 the finger 2 moves from thecentre of the transmitting LED e.g. to the right, the analogue outputsignal S17 of the comparator 16 correspondingly increases. When it hitsthe upper threshold value OS, the LED selection advances to the next LEDon the right. The sign of the output signal therefore reverses (62) andthe signal reaches the lower threshold value US. The LED selectionswitches back to the previous LED. Naturally, there is also acorresponding changeover of the LEDs connected as receivers.

Undesirable tolerances, e.g. as a result of a scratch on the translucentsurface, may lead to the situation where the LED does in fact “shift”,because the upper threshold value OS was reached without difficulty (63,FIG. 11), but afterwards the lower threshold value US after the changeof sign is no longer undershot (64, FIG. 11). If the operator in thissituation reverses the direction of the finger movement because e.g. theoperator wishes to move back from this adjusted value, the display doesnot respond and, despite movement of the finger, remains in position.This maloperation may easily be prevented in that after each change ofLED the output signal S17 is utilized in its entire magnitude from zero.Previously, it had to run through the voltage range from the upperthreshold value OS, through zero to the lower threshold value US. Upon asecond switching operation back to the original position there was afactor of uncertainty about reattainment of the lower threshold valueUS. If, however, the instantaneous output signal S17 of the comparator16 is referred to “0” at the changeover moment, the Δ of the signalstarts at zero and therefore exceeds the respective threshold value withdouble amplitude, which guarantees unconditional switching reliability.

In FIG. 12 a low pass constructed from R₃ and C₃ forms a time delay forthe signal S17 of the comparator 16. Capacitor C₂ together with switchS4 forms a referencing unit. Buffer B is used only to electricallyisolate the referencing unit C₂/S4 from the low pass R₃/C₃. D1 is adifferentiating apparatus for a counting signal of the position counter23. Each time the numerical value S23 of the position counter 23changes, a short pulse is applied via a signal line SD1 to switch S4and, when switch S4 is closed, the capacitor C₂ is discharged to zero.The output signal S17 of the comparator 16 because of the delayinglow-pass effect of the low pass R₃/C₃ at the output of the buffer Bduring the switching time of switch S4 has experienced only aninsubstantial change, so that virtually the entire Δ of the outputsignal S17 may come into effect across the input of the windowcomparator 22. Naturally, zero is only one example of a preselected orpreselectable value. Referencing may be effected also to anotherspecific preselected or preselectable value, so that after thechangeover the next threshold value US or OS is reached with part of theoutput signal S17.

With the circuit according to FIG. 12 it is guaranteed that each fingermovement is easily detected and the light-emitting LED always followsthe finger movement. In said case, only one LED emits light when thefinger is situated centrally on it, and two adjacent LEDs when thefinger is situated between them. In the latter case, the position of thelight-emitting LED alternates at a frequency determined by the low passR₃/C₃. Given suitable dimensioning, the frequency may be higher than isdetectable with the eye, so that a continuous emission of light isperceived. Analogously to the finger position between the two LEDs,there is a corresponding distribution of the intensity of theluminosity. In the embodiment, R₃ has 10 kΩ, R₄ 1 MΩ, R₅ 10 kΩ, R₆ 1 kΩand R₇ 10 kΩ. C₂ has a value of 0.1 μF and C₃ a value of 10 nF.

FIG. 13 shows the analogue output signal S17 across the output of thebuffer B (FIG. 12) when a finger is moved over the LED row withoutswitch S4 being actuated. FIG. 14 shows the same analogue output signalS17 only across the input of the window comparator 22, when the switchS4 upon each change of position refers the signal S17 to zero (71 inFIG. 14). The dashed lines 72, 73 correspond to the signal if no furtherchangeover were to occur. It is clear that the output signal S17 afterreferencing 71 would definitely exceed the threshold value OS or US,respectively, and therefore leads to a trouble-free switching operation.The steep flank arises during the referencing 71 when switch S4 for ashort time during the position switching operation discharges thecapacitor to “0”. To prevent the input voltage of the window comparator22 from “drifting away” on account of the open switch S4, a high-valueresistor R4 is connected in parallel to the switch S4. The d.c.decoupling by means of capacitor C₂ and resistor R₄ additionally alsoprevents the influence of disturbances, e.g. an asymmetry across theoutput of the comparator 16 owing to scratches on the translucentsurface. The disturbance-induced signal deviation from zero, when thefinger has been removed, is automatically referenced to zero after thecapacitor C₂.

Often, however, given a finger position between 2 adjacent LEDs, foreasier selection only one of the two LEDs should emit light. And namelythe one that is nearest to the controlling finger. In the previouslydescribed embodiment both LEDs emit light alternately, according to theconstruction so quickly that to the eye it appears like a continuousemission of light. FIG. 15 shows the signal V1, which is derived fromthe output signal S17, across the input of the window comparator 22 inFIG. 12 when the finger 2 is situated between two LEDs. AP shows theactivation phases of the two LEDs n and n+1.

In order in this situation to be able to opt for one of the two LEDs, bymeans of a hysteresis detector 84 (FIG. 16) as a decision aid a controlsignal S84 is produced for the two threshold values OS and US. Thehysteresis detector 84 checks the count value of the position counter 23(FIG. 7) for periodic counting operations with maximum countingincrements +/−1. If such a switching sequence appears in the count valueS23 for a number of periods (e.g. greater than 5) within a predeterminedtime, the hysteresis detector 84 opens the switch S5. This is always thecase when a finger is situated between two adjacent LEDs. If switch S5opens, the capacitor C₅ charges up from the threshold value preselectedby the voltage divider R₅, R₆, R₇, i.e. towards a higher potential. Insaid case, the upper threshold value rises, while the lower thresholdvalue drops.

The control device 24 therefore switches back and forth between adjacentlight-emitting diodes, if the finger 2 remains between adjacent LEDswithout changing, and increases the sensitivity for position recognitionuntil a preselected value is exceeded. Thus, in the event of repeatedswitching back and forth a decision aid is activated, which sets thereceiving element less and less sensitively until the light-emittingdiode situated closer to the body may be clearly determined. Thedecision aid then reverts to the state of sensitivity for the detectionof further movement of the finger 2.

FIG. 17 shows the variation of the threshold value OS and US. In theperiod t₁ the hysteresis detector 84 has identified at least fiveswitching operations between two adjacent LEDs and has set the controlsignal S84 to “low” so that the switch S5 has been opened. This statelasts until the signal V1 no longer exceeds the threshold values (81FIG. 17) and only one LED emits light. This is registered by thehysteresis detector 84 and it closes switch S5 again. The time constantof the capacitor C₃ and of the resistor R₅ is to be so dimensioned thatit is greater than the time constant of C₂ and R₄ in order to guaranteetrouble-free referencing of the signal V1. The circuit arrangement hasthen reattained its original sensitivity for the detection of fingermovement. The changeover of the threshold values OS and US may beeffected so quickly that a simultaneous emission of light by two LEDsoccurs for only such a short time during the finger movement that it isnot perceived by the eye.

For improved comfort a circuit may be additionally inserted, which isnot more closely designated here and which in the event of aninadvertent displacement of the finger 2 during removal results in noshift of position of the LEDs and hence of the desired control value.For this purpose, the distance signal S21 is evaluated. If thisindicates a removal of the finger with a simultaneous change ofposition, then this change of position is accordingly ignored, e.g. bydisabling the position counter 23. Preferably, a value of the deviationfrom the last signal of e.g. 10% may also be preselected. If this valueis exceeded during removal of the body, the control device 24 selectsthe LED, at which the body last dwelt for longer than a preselecteddwell time, e.g. t28.

Despite the seemingly comprehensive signal evaluation, a touch-sensitiveLED row in the form of an IC (integrated circuit) with external LEDs isperfectly easy to realize. Such an arrangement may be used for example,directly as a “volume control”, to process a digital data stream oralternatively only to output the “position” (FIG. 18 a, b, c). Measuresmay also be taken so that after disconnection of the power supply theactual counter content of the position counter 23 is retained until itis activated again. Unlike mechanical sliding controls (FIG. 19), whichgenerally comprise a straight sliding region from a point A to a pointB, the touch-sensitive LED row may be realized in any desired form ofpresentation, e.g. arc-shaped or round (FIG. 20/FIG. 21). To lengthenthe operating path, LED rows may also be cascaded. Accordingly, if thefunction of a last LED in a row is functionally linked to a first LED ofthe same row, a virtual turning knob may easily be produced (FIG. 22).

The regulating/adjusting unit 30 will generally comprise only onedisplay, i.e. only one light-emitting element. Naturally, however, theprinciple—1 transmitter, 2 receivers grouped at a small or large,uniform or non-uniform distance around the transmitter—may also betransposed. In said case, two transmitters alternately transmit and onereceiver disposed midway between the two transmitters evaluates thereflected signal. Such a circuit arrangement, but without the variationof position required for the touch-sensitive LED row, is described inthe earlier German patent application 101 33 823.6. By virtue ofautomatic correction of the received signal to zero, in theabove-mentioned circuit arrangement potentially disturbing extraneouslight influences are totally avoided.

In an arrangement with 2 transmitting elements, the finger is positionedin the “gap” between the two transmitting elements and then shifted bymoving the finger into the desired position. Naturally, here too, a“momentary contact” with the “gap” may initially activate a furthershift facility (FIG. 24).

FIG. 25 shows a complete block diagram of the “touch-sensitive LED row”.

Occasionally, a rapid change of the selected setting of theregulating/adjusting unit may also be desirable. Up until now, what hasmostly been mentioned is a momentary contact with the light-emitting LEDor the gap. It is however also possible for the entire LED row, afteradjustment has been effected, i.e. when, for example, removal of theactuating body has been recognized, to be activated at regularintervals, e.g. at a frequency not visible to the human eye, in order tocheck whether and where a body is approaching or where there ismomentary contact, and there e.g. after momentary contact to take overthe LED as a display and also correspondingly activate theregulating/adjusting unit.

It is self-evident that this description may be subject to a wide rangeof modifications, alterations and adaptations, which are in the range ofequivalents to the appended claims.

1. Circuit with an optoelectronic display unit for the discrete displayof the setting of a regulating/adjusting unit comprising: at least onedetection element configured to detect actuation of theregulating/adjusting unit by means of a body configured to change thesetting of the regulating/adjusting unit, wherein the detection elementupon actuation is configured to supply an output signal corresponding tothe desired change; a plurality of light-emitting diodes disposedsubstantially side by side in a row and configured to emit opticalradiation, the light-emitting diodes being formed as display elements onthe display unit; a control device, which, in dependence upon the outputsignal produced by the detection element, is configured to control atleast one of the light-emitting diodes to display the respectivesetting, as well as the regulating/adjusting unit to change the setting,wherein the control device is configured to control at least one of thelight-emitting diodes, the detection elements, as well as theregulating/adjusting unit to follow the movement of the body on thebasis of the output signal, which is formed in dependence upon themovement of the body relative to the light-emitting diode that isemitting optical radiation, and that either of at least two receivingelements are provided, which are configured to be sensitive to theoptical radiation of the light-emitting diodes, wherein the detectionelements detect the optical radiation emitted by at least onelight-emitting diode and reflected by the body, or at least onereceiving element is provided, which is configured to be sensitive tothe optical radiation of the light-emitting diodes, wherein thedetection element detects the optical radiation emitted by at least twolight-emitting diodes and reflected by the body, wherein in both casesthe control device, as soon as the control device because of the outputsignal advances the display unit in one direction to one of the nextlight-emitting diodes, is configured to advances in the same directionthe receiving element(s) being adjacent to the light-emitting diodeemitting the optical radiation.
 2. Circuit according to claim 1, whereinthe one direction is along the row of light-emitting diodes.
 3. Circuitaccording to claim 1, wherein the receiving element is one of thelight-emitting diodes, which is at least part of the time controlled insuch a way that upon illumination it generates a voltage.
 4. Circuitaccording to claim 1, wherein the light-emitting diodes are configuredto be operated sequentially in respect of time as transmitter andreceiving element.
 5. Circuit according to claim 1, wherein thelight-emitting diodes immediately adjacent to the light-emitting diodethat is emitting optical radiation are operated as a receiving element,and that, as soon as the control device because of the output signaladvances the display unit to the next light-emitting diode, the adjacentlight-emitting diodes operated as a receiving element are alsoconfigured to be advanced in the same direction.
 6. Circuit according toclaim 1, wherein the optical radiation emitted by the light-emittingdiode is modulated by a clock generator, and connected downstream of thereceiving elements is a synchronous demodulator configured to recognizethe modulated light reflected by the body.
 7. Circuit according to claim1, wherein a momentary contact recognition apparatus with a surface inthe vicinity of the light-emitting diode is provided, which isconfigured to activate a timer, which is configured to enable theactuation of the display unit.
 8. Circuit according to claim 7, whereinthe light-emitting diodes and the receiving elements form at least tworeflection sections and that, for recognition of the momentary contact,the individual signals resulting therefrom are supplied to a summingstage to form a signal of the distance from the surface of or in thevicinity of the surface of the light-emitting diode.
 9. Circuitaccording to claim 7, wherein the momentary-contact recognitionapparatus is configured to recognize as momentary contact a pattern ofmotion, which comprises the approach of the body, the sudden braking ofthe body against a momentarily touched surface as well as a dwelling onthe surface for a pre-selected time.
 10. Circuit according to one ofclaim 7, wherein the momentary-contact recognition apparatus isconfigured to recognize as momentary contact only a repeated momentarycontact.
 11. Circuit according to claim 1, wherein the light-emittingdiodes and the receiving elements form at least two reflection sections,and a comparator compares individual signals resulting therefrom inorder to decide about the direction of motion in order to generate adigital output signal.
 12. Circuit according to claim 1, wherein thelight-emitting diodes and the receiving elements form at least tworeflection sections, and a position recognition comparator comparesindividual signals resulting therefrom in order to decide about thechangeover instant between two adjacent light-emitting diodes togetherwith formation of an analogue output signal for the position of theobject.
 13. Circuit according to claim 1, wherein, for a light-emittingdiode located at the end of the row, a simulation circuit is configuredto simulate a light signal at the side remote from the light-emittingdiode, which is adjacent to the light-emitting diode located at the endof the row.
 14. Circuit according to claim 13, wherein at the simulationcircuit a voltage divider is provided, the divider ratio of which beingdimensioned so that the divided-down transmitted clock signal of theclock generator at the side, where the light signal is simulated, is atleast slightly greater than the reception signal of the adjacentlight-emitting diode produced by parasitic reflection at the translucentsurface.
 15. Circuit according to claim 1, wherein the control device onthe basis of the output signals is configured to control thelight-emitting diodes in such a way that the light-emitting diodeforming the display element is situated under the body.
 16. Circuitaccording to claim 15, wherein the control device, when the body remainsin an unvarying position between adjacent light-emitting diodes, isconfigured to switch back and forth between the adjacent light-emittingdiodes, and increase the sensitivity for position detection until apreselected value is exceeded.
 17. Circuit according to claim 16,wherein in the event of repeated switching back and forth, a decisionaid is activated that sets the receiving element less and lesssensitively until the light-emitting diode situated closer to the bodyis selectable and which then reverts to the state of sensitivity for thedetection of further movement of the body.
 18. Circuit according toclaim 17, wherein the decision aid is a hysteresis detector.
 19. Circuitaccording to one of claims 16, wherein the output signal at a instant ofa changeover is referred to a specific preselected or preselectablevalue so that after the changeover a next threshold value is reachedwith a part of the output signal.
 20. Circuit according to claim 1,wherein the output signal for the position of the body is ignored if atthe same time a signal of the distance from the surface of or from thevicinity of the surface of the light-emitting diode changes withsimultaneous removal of the body from the light-emitting diode. 21.Circuit according to claim 20, wherein, when the output signal for theposition of the body during removal varies by more than a preselectedvalue, the control device selects the light-emitting diode, at which thebody last dwelt for longer than a preselected dwell time.
 22. Circuitaccording to claim 1, wherein storage means are provided, and configuredto store a last setting even in a de-energized state.
 23. Circuitaccording to claim 1, wherein a plurality of rows of light-emittingdiodes are cascaded in order to lengthen the operating path.
 24. Circuitaccording to claim 1, wherein a last light-emitting diode of the row isfunctionally linked to a first light-emitting diode of the same row withsimultaneous formation of a virtual turning knob.
 25. Circuit accordingto claim 1, wherein the light-emitting diodes are arranged in the shapeof an arc or circle.
 26. Circuit according to claim 1, wherein thecontrol device is configured to operate all of the light-emitting diodesup to a position of the body and/or up to a position of the receivingelement as display elements to form a light strip.